Move GetStringLength and helper from SimplifyLibCalls to ValueTracking.

No functionality change.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@97793 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 0 insertions, 124 deletions

diff --git a/lib/Transforms/Scalar/SimplifyLibCalls.cpp b/lib/Transforms/Scalar/SimplifyLibCalls.cpp
index cde214b..5eae7b3 100644
--- a/lib/Transforms/Scalar/SimplifyLibCalls.cpp
+++ b/lib/Transforms/Scalar/SimplifyLibCalls.cpp
@@ -433,130 +433,6 @@ void LibCallOptimization::EmitFWrite(Value *Ptr, Value *Size, Value *File,
 // Helper Functions
 //===----------------------------------------------------------------------===//
 
-/// GetStringLengthH - If we can compute the length of the string pointed to by
-/// the specified pointer, return 'len+1'.  If we can't, return 0.
-static uint64_t GetStringLengthH(Value *V, SmallPtrSet<PHINode*, 32> &PHIs) {
-  // Look through noop bitcast instructions.
-  if (BitCastInst *BCI = dyn_cast<BitCastInst>(V))
-    return GetStringLengthH(BCI->getOperand(0), PHIs);
-
-  // If this is a PHI node, there are two cases: either we have already seen it
-  // or we haven't.
-  if (PHINode *PN = dyn_cast<PHINode>(V)) {
-    if (!PHIs.insert(PN))
-      return ~0ULL;  // already in the set.
-
-    // If it was new, see if all the input strings are the same length.
-    uint64_t LenSoFar = ~0ULL;
-    for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
-      uint64_t Len = GetStringLengthH(PN->getIncomingValue(i), PHIs);
-      if (Len == 0) return 0; // Unknown length -> unknown.
-
-      if (Len == ~0ULL) continue;
-
-      if (Len != LenSoFar && LenSoFar != ~0ULL)
-        return 0;    // Disagree -> unknown.
-      LenSoFar = Len;
-    }
-
-    // Success, all agree.
-    return LenSoFar;
-  }
-
-  // strlen(select(c,x,y)) -> strlen(x) ^ strlen(y)
-  if (SelectInst *SI = dyn_cast<SelectInst>(V)) {
-    uint64_t Len1 = GetStringLengthH(SI->getTrueValue(), PHIs);
-    if (Len1 == 0) return 0;
-    uint64_t Len2 = GetStringLengthH(SI->getFalseValue(), PHIs);
-    if (Len2 == 0) return 0;
-    if (Len1 == ~0ULL) return Len2;
-    if (Len2 == ~0ULL) return Len1;
-    if (Len1 != Len2) return 0;
-    return Len1;
-  }
-
-  // If the value is not a GEP instruction nor a constant expression with a
-  // GEP instruction, then return unknown.
-  User *GEP = 0;
-  if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(V)) {
-    GEP = GEPI;
-  } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
-    if (CE->getOpcode() != Instruction::GetElementPtr)
-      return 0;
-    GEP = CE;
-  } else {
-    return 0;
-  }
-
-  // Make sure the GEP has exactly three arguments.
-  if (GEP->getNumOperands() != 3)
-    return 0;
-
-  // Check to make sure that the first operand of the GEP is an integer and
-  // has value 0 so that we are sure we're indexing into the initializer.
-  if (ConstantInt *Idx = dyn_cast<ConstantInt>(GEP->getOperand(1))) {
-    if (!Idx->isZero())
-      return 0;
-  } else
-    return 0;
-
-  // If the second index isn't a ConstantInt, then this is a variable index
-  // into the array.  If this occurs, we can't say anything meaningful about
-  // the string.
-  uint64_t StartIdx = 0;
-  if (ConstantInt *CI = dyn_cast<ConstantInt>(GEP->getOperand(2)))
-    StartIdx = CI->getZExtValue();
-  else
-    return 0;
-
-  // The GEP instruction, constant or instruction, must reference a global
-  // variable that is a constant and is initialized. The referenced constant
-  // initializer is the array that we'll use for optimization.
-  GlobalVariable* GV = dyn_cast<GlobalVariable>(GEP->getOperand(0));
-  if (!GV || !GV->isConstant() || !GV->hasInitializer() ||
-      GV->mayBeOverridden())
-    return 0;
-  Constant *GlobalInit = GV->getInitializer();
-
-  // Handle the ConstantAggregateZero case, which is a degenerate case. The
-  // initializer is constant zero so the length of the string must be zero.
-  if (isa<ConstantAggregateZero>(GlobalInit))
-    return 1;  // Len = 0 offset by 1.
-
-  // Must be a Constant Array
-  ConstantArray *Array = dyn_cast<ConstantArray>(GlobalInit);
-  if (!Array || !Array->getType()->getElementType()->isIntegerTy(8))
-    return false;
-
-  // Get the number of elements in the array
-  uint64_t NumElts = Array->getType()->getNumElements();
-
-  // Traverse the constant array from StartIdx (derived above) which is
-  // the place the GEP refers to in the array.
-  for (unsigned i = StartIdx; i != NumElts; ++i) {
-    Constant *Elt = Array->getOperand(i);
-    ConstantInt *CI = dyn_cast<ConstantInt>(Elt);
-    if (!CI) // This array isn't suitable, non-int initializer.
-      return 0;
-    if (CI->isZero())
-      return i-StartIdx+1; // We found end of string, success!
-  }
-
-  return 0; // The array isn't null terminated, conservatively return 'unknown'.
-}
-
-/// GetStringLength - If we can compute the length of the string pointed to by
-/// the specified pointer, return 'len+1'.  If we can't, return 0.
-static uint64_t GetStringLength(Value *V) {
-  if (!V->getType()->isPointerTy()) return 0;
-
-  SmallPtrSet<PHINode*, 32> PHIs;
-  uint64_t Len = GetStringLengthH(V, PHIs);
-  // If Len is ~0ULL, we had an infinite phi cycle: this is dead code, so return
-  // an empty string as a length.
-  return Len == ~0ULL ? 1 : Len;
-}
-
 /// IsOnlyUsedInZeroEqualityComparison - Return true if it only matters that the
 /// value is equal or not-equal to zero.
 static bool IsOnlyUsedInZeroEqualityComparison(Value *V) {